Big difference...

Between the L-150 and the L-150A's. Probably because the L-150A uses a variant of the vaunted 3113B crossover, found in the L-112 and the L-96. My unmod'd L-150's sounded somewhat weak with none of the presence and power of my old L-65A's. My little brother brought up his L-150's to be mod'd, but I didn't know they were A models, so I decided to A-B compare the two. My little brother's L-150A's sound just like my heavily modified speakers. I could've saved myself a whole lot of trouble and just swapped out the crossovers first! I didn't know they'd make that much of a difference. Same speaker, same cab, almost identical components. I take back everything I said about the 128H woofer. It is plenty healthy. If you look at the L-150 crossover, there's a bunch of 'extra' discrete components in the LF. Look at the L-150A and it is very simple, one resistor in the LF loop, vs four for the L-150. Even the mid-range is different and there's far more projection and details in the "A" than the other.

Compare the two for yourself, the L-150 X-over
http://manuals.harman.com/JBL/HOM/Te.../L150%20ts.pdf

L-150A X-over
http://manuals.harman.com/JBL/HOM/Te.../L150%20ts.pdf

One good thing about the A-B test, is that I had FOUR of these big speakers arrayed on both sides of the entertainment center. It looked like a wall of sound! As Bo said about the gear, "...A lot of gear is great; more is better. Too much gear is just right..." That's for sure. The sound output was astonishing. Two 2214's, two 128H's, four LE5's and a pair of 033's and 044's rounded it out! Bass output was comparable to many theatre's I've been to and even night clubs. The big Sansui G had no sweat beating the walls of my listening room half to death! I was grinning like a mad scientist. Put some 'House' music on and had the grills off. What a show, the black and white woofer cones were pumping furiously! Now I've got to go out and get another pair of these things. Damn you Bo!